1. Field of the Invention
This invention relates to attachments for display position indicators, and more particularly to a holder for such an indicator which utilizes ball bearing-mounted spheres in order to provide for smoother and faster movement of the indicator and thereby enable more accurate positioning of a cursor on a display screen.
2. Prior Art
U.S. Pat. No. 3,835,464 to Rider, incorporated herein by reference, discloses a typical position indicator used to control the movement of a cursor on the visual display of a cathode ray tube. Such a position indicator device is commonly referred to as a "mouse". The mouse generates signals indicative of its position on a supporting surface such as a desk top, which causes the cursor on the screen to be moved in a manner corresponding to the movement of the mouse on the supporting surface. The mouse includes a control mechanism that comprises a transport sphere which is in contact with position wheels indicative of Cartesian coordinates. The movement of the mouse over the supporting surface causes the sphere to rotate about its radius. The radial rotation of the sphere is in turn translated into Cartesian coordinates by the resulting movement of the position wheels which are in contact with the sphere. These coordinates are used to reposition the cursor on the display screen accordingly.
A positioning device such as that disclosed in Rider provides an easy method for positioning a cursor on a visual display. These devices have proved very useful when used in conjunction with many of the personal computers now commercially available, such as the Lisa or Macintosh made by Apple Computer. The devices are especially well-suited to graphic applications in which the mouse acts as a kind of electronic "brush" which allows a user to create his own visual images on the video display "canvass". Such devices can also be used in word-processing applications and with entertainment and data base programs.
Because the spherical transport ball of the mouse extends beyond the housing in which it is situated, the device requires some type of stablizing means so as to provide for even support of the mouse and to keep the housing itself off of the supporting surface. In order to accomplish this, most mouse devices have stabilizing structures known as "feet" which are mounted to the bottom of the housing and come in contact with the supporting surface. With the addition of two such feet a tripodal support arrangement can be provided using the spherical transport ball as the third leg of the tripod.
However, the tripod arrangement as well as other such stabilization configurations have the drawback that the feet wear out after repeated uses of the mouse. When this happens, movement of the mouse is made more difficult. Therefore, it is one object of the present invention to provide a device that can be attached to a mouse in order to provide stability as well as to protect the feet of the device from wearing out.
It is a further object of the present invention to provide a means for reducing the friction between the mouse and the supporting surface, thereby allowing movement of the mouse with less effort and providing for greater control of the movement of the mouse and associated cursor positioning.
It is still another object of the present invention to allow a mouse to move over rougher surfaces with greater ease and with less effort than would normally be possible because of the friction created by the rubbing of the feet over the surface.
Other objects of the present invention will be evident from the description hereinafter presented.